Manufacture of rot resistant sponges



3,197,327 :nted July 27, 1965 3,197,327 MANUFACTURE OF ROT RESISTANT SPONGES Harold L. Dillon, Columbia, Tenn., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware No Drawing. Filed Sept. 27, 1961, Ser. No. 140,988 8 Claims. (Cl. 11798) This invention relates to the preparation of cellulosic sponges and, more particularly, to prolonging the useful life of such sponges.

In the manufacture of cellulose sponges, an alkaline cellulose solution, such as viscose, is mixed with a poreforming material together with some fibrous material. Salt crystals, such as decahydrated sodium sulfate (Glaubers salt), are generally used as the pore-forming material and cotton, flax or hemp fibers have been employed as the fibrous material. This mixture is formed into a paste which is introduced into molds where coagulation and decomposition or regeneration are accomplished in a manner well known to those skilled in the art. Salts and other impurities are then washed from the shaped regenerated cellulose articles to form the regenerated cellulose sponge. As the final treatment in a series of wet treatments, the sponges are usually subjected to a softening bath consisting essentially of diethylene glycol or glycerol or the like dissolved in water.

The cellulosic sponges are subject to degradation by molds and bacteria. Preservatives to resist degradation of cellulose are known but are diflicult to retain in a cellulosic sponge during use, since they tend to be leached therefrom during use which involves repeatedly immersing the sponge in water and squeezing excess Water there from. Water-insoluble preservatives do not lend themselves well to aqueous processing which is characteristic of the manufacture of cellulosic sponges.

US. Patent 2,945,772 describes a cellulose sponge resistant to degradation by molds and bacteria which has incorporated therein a mixture of rosin amine and a quaternary ammonium halide. The product described in US. Patent 2,945,772 retains about 50% of its original tensile strength after being leached about fifty times and then subjected to a six day simulated soil burial test, and only 15-20% of its original tensile strength after same number of leaches and a thirteen day simulated soil burial test.

It has now been discovered that still further improvements can be made in cellulose sponges in a variety of forms, such as blocks, sheets and yarns, whereby they retain as much as 90%-100% of their original tensile strength and essentially no loss in weight after being leached fifty times and then subjected to a seven day simulated soil burial test.

It is the object of the present invention to provide a cellulosic sponge material highly resistant to deterioration. It is a further object to increase the useful life of such a sponge. A still further object is the provision of a cellulose sponge resistant to attack by molds and/ or bacteria. Other object will appear hereinafter.

The foregoing objects are accomplished by uniformly impregnating a cellulosic sponge material with a cationic rosin amine and/ or a cationic quaternary ammonium halide and then treating the impregnated cellulose sponge with an anionic surfactant. The anionic surfactant reacts with the cationic rosin amine and/or the cationic quaternary halide to form a water-insoluble precipitate which is resistant to leaching with water.

The sponge material is first impregnated with a cationic surfactant comprising about a 2% aqueous solution of a rosin amine and/ or quaternary ammonium halide in suffiicent quantity to deposit about 1% of the rosin amine and/or quaternary ammonium halide throughout the sponge, the percentage being based on the weight of the cellulose in the sponge. Preferably, before the sponge is allowed to dry, it is then impregnated with about a 1% aqueous solution of an anionic surfactant which reacts with the rosin amine and/ or the quaternary ammonium halide to form a relatively water-insoluble nonionic precipitate which is resistant to leaching by water and imparts to the sponge surprising resistance to degradation by molds and bacteria.

It is also possible to reverse the order of impregnating the sponge with the preservative materials, i.e., the sponge can be first impregnated with the anionic surfactant and subsequently impregnated with the cationic rosin amine and/ or the quaternary ammonium halide.

The most useful rosin amine in the present invention is Rosin Amine D, dehydroabietyl amine manufactured by Hercules Powder Company; and the most useful quaternary ammonium halides are Arquad 16, an alkyl trimethyl ammonium chloride containing hexadecyl trimethyl ammonium chloride, 6% octadecyl trimethyl ammonium chloride and 4% octadecenyl trimethyl ammonium chloride manufactured by Armour & Company; and Hyamine 1622, a diisobutyl phenoxy ethoxyethyl dimethyl benzyl ammonium'chloride monohydrate manufactured by Rohm and Haas Company.

It is possible to incorporate a sponge softener in the last;

, J 2,698,625. Useful products can also be made by immers-x a? ing the sponge containing the water-insoluble preservatives of this invention in a softener bath as a final operation prior to cutting the sponge in sizes for ultimate use and packaging them in moisture-proof containers as described in US. Patents 2,613,862 and 2,613,487.

The rosin amines useful in the present invention include primary amines derived from stabilized rosins and stabilized rosin acids wherein the carboxyl group has been converted into a --CH NH group. These include dehydroabietyl amine derived from dehydrogenated rosin; dihydroand tetra-hydroabietyl amines derived from hydrogenated gum or wood rosin; and the aforementioned amines derived from pure stabilized rosin acids. Stabilized rosin amine is meant to include primary amines having a ring structure of a stabilized rosin acid, sfich as dehydro-, dihydro-, tetrahydroor polyabietic acid or a mixture of such primary amines. It should be understood that dehydroabietyl amines and the other hydro abietyl amines refer to rosin amines wherein the aforementioned amines are the major constituents. It is not intended that minor amounts of other materials derived from the dehydrogenated rosins or hydrogenated rosins be excluded when preparing the aforementioned rosin amines.

The quaternary ammonium halides useful in the present invention are those that are water soluble and in which the halogen is either fluorine, chlorine, bromine or iodine. Preferred quaternary halides include lauryl dimethyl benzyl ammonium chloride, cetyl trimethyl ammonium chloride, cetyl dimethyl ethyl ammonium chloride, tridecyl benzyl hydroxyethyl imidazolinium chloride, lauryl pyridium chloride, myristamido propyl dimethyl benzyl ammonium chloride, stearyl trimethyl ammonium bromide, octadecyl dimethyl benzyl ammonium bromide, and diisobutyl phenoxy ethoxy ethyl dimethyl benzyl ammonium chloride. The corresponding fluorides and iodides are also useful in practicing this invention.

The anionic surfactant useful in this invention can be any one of a large number of such compounds which are well known, such as those described in Encyclopedia of Chemical Technology, by Kirk et al., vol. 13, pp. 521- 528, published 1954 by Interscience Publishers, Inc., New York, NY. The most useful anionic surfactants include sodium N-methyl-N-palmitoyl taurate, sodium dioctyl sulfosuccinate, salts of alkyl aryl sulfonates, such as the ammonium or alkali metal (e.g. sodium of potassium), salts of dodecyl benzene sulfonate, and propyl naphthalene sulfonate, and the alkali metal salts of phenolic compounds, such as the sodium salt of orthobenzyl-parachlorophenol.

When a mixture of the rosin amine and quaternary ammonium halide is used for the cationic impregnant, it can be prepared in several ways. The rosin amine and the quaternary ammonium halide can be first mixed together and then emulsified by slowly adding water while agitating the mixture. Alternatively, the mixture can be dissolved in a solvent such as diethylene glycol. As another alternative, the quaternary ammonium halide can first be dissolved in water to form a solution. To this solution, the rosin amine can be slowly added with constant stirring. After additional dilution with water, this solution of the mixture can be used as the first or second impregnating bath. If the cationic impregnant mixture is used as the second impregnating bath for forming the insoluble preservative, it can be added to the sponge-softener bath.

It i immaterial how the sponges are impregnated with the separate anionic and cationic surfactants. The impregnating compositions can be applied to the sponge by soaking, spraying or by alternately squeezing the sponges and applying the liquid between rolls. The degree of protection to deterioration imparted to the sponge varies with the amount of insoluble preservative (reaction product of anionic and cationic surfactants) incorporated in the sponge, and can be regulated by the concentration of the anionic and cationic surfactants in the separate impregnating baths; the length of time of treatment; and the temperature of the processing, and amount of squeezing to which the sponge is subjected. Preferably the cationic rosin amine and/ or quaternary ammonium halide is dissolved and/ or dispersed to the extent of about .2% in water. The cellulose sponge, prepared in the conventional manner as described in US. Patents 2,280,022 and 2,295,823, is passed through the solution or dispersion, the exposure being about three to five minutes. After excess solution or dispersion is squeezed from the sponge, the quantity of rosin amine and/or quaternary ammonium halide remaining represents about 1% of the weight of the cellulose in the sponge. Before the sponge is dried, it is immersed in an aqueous solution of anionic surfactant of about stoichiometric concentration which reacts with the rosin amine and/or quaternary ammonium halide to form a water-insoluble, non-ionic precipitant in the sponge.

Useful products can be made by impregnating the cellulose sponge with as little as about .1%, and as much as about 5% or higher of the cationic rosin amine and/ or cationic quaternary ammonium halide, based on the weight of cellulose in the sponge. If amounts less than about .1% are used, there is no significant improvement with respect to resistance to degradation of the sponge. If amounts appreciably greater than about 5.0% are used, there is no appreciable improvement in resistance to degradation and other valuable properties of the sponge may be deleteriously aifected.

The preferred amount of anionic surfactant incorporated in the sponge in accordance with this invention is the amount which will react stoichiometrically with the cationic compound(s) introduced in the sponge. Useful products can be made by incorporating greater or lesser amounts of the anionic compounds. For example, the amount of anionic compound can be that which reacts with only about 50% of the cationic compound Where the amount of the cationic compound corresponds to about .2% based on the weight of the cellulose sponge. There is no particular advantage to be gained by adding more than a stoichiometric amount of the anionic compound, although there is no particular disadvantage in doing so.

The invention will be more clearly understood by referring to the examples and discussion which follow. The examples are specific embodiments of the invention and are not to be considered as limiting the invention in any manner. The examples set forth are the best modes contemplated for carrying out the invention. Unless otherwise stated, all percentages in the examples, as well as in the specification and claims, are by weight.

EXAMPLE I A cellulose sponge made in a conventional manner, such as in accordance with US. Patent 2,280,022, and washed free of the Glaubers salt is immersed in a .2% aqueous solution of Arquad 16 hexadecyl trimethyl ammonium chloride, 5% octadecyl trimethyl ammonium chloride, and 4% octadecenyl trimethyl ammonium chloride) to saturate the sponge. The excess solution is squeezed from the sponge by passing it between squeeze rolls. The weight of the solution remaining in the sponge equals about 4 to 5 times the weight of the sponge thus distributing throughout the sponge about 1% of the Arquad 16 based on the weight of the cellulose in the sponge.

While the sponge containing the Arquad 16 is still wet, it is immersed in a 1% aqueous solution of sodium dodecyl benzene sulfonate until the sponge is thoroughly saturated. The excess solution of the sulfonate is squeezed from the sponge and the solution remaining distributed throughout the sponge is approximately the amount to react in stoichiometric proportion with the Arquad 16. The cationic surfactant (Arquad 16) reacts with the anionic surfactant (sodium dodecyl benzene sulfonate) within the sponge to form in situ a water-insoluble preservative. The sponge produced as described above, together with three separate controls, were tested for resistance to degradation, when exposed to mold and bacteria, in the following manner to simulate soil burial:

(1) The test specimens (including controls) were separated into four groups of nine each. One group, to be used as controls, was tested for tensile strength to determine the original tensile strength for all groups. Another group was not leached, another group was leached with water three times and another group was leached with water fifty times. Each leach consisted of immersing the sponge in fresh water until .it was thoroughly wet, then removing and wringing the s'ponge.

(2) The sponges to be tested were each painted on two sides with a slurry of well-composted garden soil in water until the weight of each painted sponge was about six times its original weight.

(3) The soil-impregnated sponges were placed in polyethylene bags and then squeezed to distribute the soil uniformly throughout the sponge. The bags were sealed by use of metal staples to minimize the water evaporation but not to provide an air-tight seal.

(4) The bags of sponges were placed in a heated cabinet maintained at 36 i1 0., the edge of the sponge resting on a shelf in the cabinet, for a period of seven days. The bags were rotated through 180 after the first three days of the test period.

(5) The exposed sponges were tested for tensile strength, and the strength retained was obtained from the following formula:

to the present example after zero, three and fifty leaches and exposure of seven days to the above described rotting conditions are compared to those of three controls described below:

For Control A, a mixture of Rosin Amine D and Arquad 16 (Example 1 of US. Patent 2,945,772) was added to the sponge and the sodium dodecyl benzene sulfonate bath was omitted; for Control B only Arquad 16 was added to the sponge and the sodium dodecyl ben zene sulfonate bath was omitted; and for Control C where no preservative was added.

A cellulose sponge prepared in the conventional manner is immersed in an aqueous bath containing about 0.08% Rosin Amine D and 0.6% Arquad 16. The excess solution is squeezed from the sponge by passing the sponge between squeeze rolls. The sponge is thus impregnated throughout with about 1% of the combined ingredients, based on the weight of the dry cellulose in the sponge. While the sponge is still wet, it is immersed in a 1% aqueous solution of sodium dodecyl benzene sulfonate until the sponge is thoroughly saturated. The excess solution is squeezed from the sponge, and the sponge is impregnated throughout with approximately the amount of sodium dodecyl benzene sulfonate to react in stoichiometric proportion with the Arquad 16 and Rosin Amine D.

Sponge specimens were then tested in the manner described in Example I.

In Table II results from the sponge treated according to the present example after zero, three and fifty leaches and exposure to seven days of exposure to the rotting conditions are compared to those of three controls A, B and C described above. The controls were prepared and tested at the same time as those of Example II using same lots of material.

Table II Percent Tensile Strength Retained (Average of 9 Specimens) After Seven Number of Times Sponges Days Exposure to Rotting Conditions Previously Leached Example Control Control Control II A B C EXAMPLE III tion is squeezed from the sponge and the sponge is impregnated with the amount of sodium dodecyl benzene sulfonate throughout the sponge to react in stoichiometric proportions with the cationic compounds.

Sponge specimens of Example III and the Controls A, B, and C prepared as described above were concurrently exposed to the modified soil burial test in the manner described in Example I. Table III shows the results for the sponges treated according to the present example after zero, three and fifty leaches followed by exposure to seven days of rotting and then tested for tensile strength as described in Example I Table III Percent Tensile Strength Retained (Average of 9 Specimens) After Seven Previously Leeched Example Control Control Control III A B C EXAMPLE IV A cellulose sponge cloth approximately .08 inch thick reinforced with a 6 x 6 mesh (threads per inch) net of cotton is immersed in an 0.20% aqueous solution of Arquad 16. The excess solution is squeezed from the sponge cloth by passing the sponge between squeeze rolls. The sponge cloth is thus impregnated throughout with about 1% of Arquad 16, based on the weight of the dry cellulose in the sponge cloth. While the sponge cloth is still wet, it is immersed in a 1% aqueous solution of sodium dodecyl benzene sulfonate until the sponge is thoroughly saturated. The excess solution is squeezed from the sponge, and the sponge is impregnated throughout with the amount of sodium dodecyl benzene sulfonate to react in stoichiometric proportions with the cat ionic compounds.

A Control D for Example IV was prepared in a similar manner except that only the Hyamine-1622 preservative was added and the sodium dodecyl benzene sulfonate was omitted. In the case of the sponge structures having a fabric insert for strength reinforcement, a weight loss determination is made rather than a tensile strength loss after the modified soil burial test, since the fabric insert does not decay at the same rate as cellulose sponge and thus the tensile strength loss is not a true measure of the amount of degradation of the cellulose sponge.

The sponge cloth was tested for resistance to degradation when exposed to mold and bacteria in the following manner:

Twenty-seven specimens of Example IV and a similar number for the control were separated into three sets of nine each.

(1) The moisture free weight was determined for each set of test specimens before exposing to rotting conditions by Weighing a moisture free sample comparable to that to be tested.

(2) One set of specimens to be tested was not leached in water, one set was leached three times and the third set was leached fifty times. Each leach consisted of immersing the sponge in fresh water until it was thoroughly wet, then removing and wringing the sponge.

(3) The sponge cloths to-be tested were each painted on their two large faces with a slurry of 'well composted garden soil in water until the weight of each sponge was about six times its original weight.

(4) The soil impregnated sponge cloths were placed in polyethylene bags and squeezed in the bags so distribute soil uniformly throughout the sponge cloth. The bags were sealed with staples to minimize water evaporation but not to provide an air tight seal.

The bags of sponge cloths were placed in a heated cabinet maintained at 36 l C. for seven days. The bags were turned over after about three days.

(6) The exposed sponge cloths were washed in a home laundry washing machine for 72 hours to remove the soil and decayed cellulose and dried to moisture-free dryness, and the percent retained weight was obtained from the following formula:

Table IV Percent Weight Retained Alter Seven Days Exposure to Number of Times Sponges Leached Rotting Conditions Example Control IV D A cellulose @ge c lgfi h approximately 0.08 inch thick, reinforced with a 6 x 6 mesh (threads per inch) net of cotton, is immersed in a 0.20% aqueous solution of Hyamine 1622. The excess solution is squeezed from the sponge by passing the sponge betwen squeeze rolls. The sponge is thus impregnated with about 1% Arquad 16, based on the Weight of dry cellulose in the sponge, throughout the sponge. While the sponge is still wet, it is immersed in a 1.0% aqueous solution of sodium dodecyl benzene sulfonate until the sponge is thoroughly saturated. The excess solution is squeezed from the sponge, and the sponge is impregnated with the amount of sodium dodecyl benzene sulfonate throughout the sponge to react in stoichiometric proportions with the catinoic compounds. Sponge specimens were then tested in the manner described in Example IV.

In Table V results for the sponge treated according to the present example after zero, three and fifty leaches and exposure to seven days of rotting are compared to those of Control D which Was the same as those employed for Example IV.

Table V Percent Weight Retained After Seven Days Exposure to Number of Times Sponges Previously Rotting Conditions Leeched Example Control V D While the above described invention will find its greatest utility in the treatment of cellulose sponges, it is also useful in treating other cellulose structures, such as, e.g., woven, knitted and non-woven fabrics containing cellulose fibers to render them rot resistant.

I claim:

1. A419} resistant cellulose sponge structure having incorpprated therein a water-insoluble reaction product of (a) a cationic compound selected from the class consisting of alrosin amine, a quaternary ammonium halide and mixtures thereof; arTlTbj'an anionic surfactant.

2. A rot resistant cellulose sponge structure having incorporated therein the water-insoluble reaction product of (1) a cationic quaternary ammonium halide and (2) an anionic alkaline salt of an alkyl aryl sulfonate.

3. The product of claim 2 in which the quaternary ammonium halide is a tetraalkyl ammonium chloride and said salt is sodium dodecyl benzene sulfonate.

4. A rot resistant cellulose sponge structure having incorporated therein the water-insoluble reaction product of (1) a quaternary ammonium chloride and (2) the sodium salt of an alkyl aryl sulfonate.

5. A rot resistant cellulose sponge structure having incorporated therein the Water-insoluble reaction product of (1) a cationic mixture of a rosin amine and a quaternary ammonium halide and (2) an anionic alkaline salt of an alkyl aryl sulfonate.

6. The product of claim 5 in which said salt is sodium dodecyl benzene sulfonate.

7. The product of claim 6 in which the rosin amine is dehydroabietyl amine and the quaternary ammonium halide is an alkyl trimethyl ammonium chloride.

8. A process for rendering cellulose sponge structures rot resistant which comprises impregnating said structure with a cationic material selected from the class consisting of a rosin amine, a quaternary ammonium halide and mixtures thereof, separately incorporating an anionic surfactant in said structure, causing said anionic and cationic material to react and form in situ a water-insoluble preservative within said structure.

References Cited by the Examiner UNITED STATES PATENTS 2,282,988 5/42 Creely 117-138.5 2,945,772 7/60 James 11798 3,018,192 l/62 Hennemann et a1. 11798 RICHARD D. NEVIUS, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,197,327 July 27, 1965 Harold L. Dillon It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 58, for "object" read objects line 68, for "2%" read .2% column 7, line 1, for "50" read to line 55, for "catinoic" read cationic Signed and sealed this 8th day of March 1966.

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ttest:

RNEST W. SWIDER EDWARD J. BRENNER :testing Officer Commissioner of Patents 

8. A PROCESS FOR RENDERING CELLULOSE SPONGE STRUCTURE ROT RESISTANT WHICH COMPRISES IMPREGNATING SAID STRUCTURE WITH A CATIONIC MATERIAL SELECTED FROM THE CLASS CONSISTING OF A ROSIN AMIN,E A QUATERNARY AMMONIUM HALIDE AND MIXTURES THEREOF, SEPARATELY INCORPORATING AN ANIONIC SURFACTANT IN SAID STRUCTURE, CAUSING SAID ANIONIC AND CATIONIC MATERIAL TO REACT AND FORM IN SITU A WATER-INSOLUBLE PRESERVATIVE WITHIN SAID STRUCTURE. 